Because of the secrecy surrounding the screening of Syrian refugees, a Republican congressman is asking President-elect Donald Trump to uphold his campaign promise to halt the refugee resettlement program and imploring President Barack Obama to declassify that vetting process.

Republican Wisconsin Rep. Sean Duffy is asking the president-elect to halt refugee resettlement at least until “confidence” in the program is realized.

In a Dec. 21 letter to Trump first obtained by the Washington Free Beacon, Duffy wrote, “Many of my constituents supported your candidacy in part because of your pledge to put a pause on the refugee resettlement program from places with high risks of terrorists until we have the confidence that we can properly screen refugees to determine whether they pose a threat to the United States. Accordingly, I ask that you uphold this campaign promise after you are sworn in as the 45th President on January 20, 2017.”

In the wake of this week’s Berlin terrorist attack — where the chief suspect is a Muslim refugee — Duffy is also demanding from the Obama administration verification that the government’s screening process is sufficiently rigorous to keep terrorists out.